I wouldn't bother about wich engine is best. All are great these days.
I have had the Yamaha F115 wich should be one of the best and had some trouble with fuel in the cranckase. Now it's giving a strange beeping noise when at low revs.
Better take a good look at the prices. I don't know if our prices in Holland are about the same as yours but Suzuki gives great prices and come standard with a SS prop and remotecontrol. Yamaha doesn't. I don't know how Merc and Mar come standard.
The new Johnson range is simply Suzuki engines and are about the same price.
Don't see so many Mercury Fourstrokes though. Do see the Mariners FS much.
Really see a lot of Mercury Optimaxes because of there weight. Just bought a 225 Optimax and that's 50 kilo's less then a F225 Yam.
Put some prices next to each other and notice the extra's that should be bought also.
Then try to find, why one is a lot more expensive then one other.
Good luck, it's a difficult job to spend much money